Thanks for the feedback. This library is, as you can guess from its name, designed to process text mainly written in Japanese. In context of Japanese, Greek and Cyrillic letters have traditionally been considered Zenkaku. See e.g., https://ja.wikipedia.org/wiki/%E5%85%A8%E8%A7%92%E3%81%A8%E5%8D%8A%E8%A7%92 for background. So this is by design.

The library also provides finer-grained character types and the methods can take target character types as a parameter. So you can exclude Greek and Cyrillic letters from the target if it is the requirement of your application. Also, if you want a more international solution, not just Japanese, I recommend using a library handling Unicode and use its East_Asian_Width attribute.

I don't understand. Characters such as Ω are not zenkaku (double-width) characters. At a minimum, they should be renamed to HAN_GREEK / HAN_CYRILLIC